In a fuel cell stack, as one example, a membrane-electrode assembly (MEA) is formed with an anode-side electrode, an electrolyte membrane, and a cathode-side electrode, a fuel battery cell is formed with the membrane-electrode assembly and a separator, and a plurality of fuel battery cells are layered to form a fuel battery cell layered structure. More specifically, each fuel battery cell is formed by placing the anode-side electrode on one surface of the electrolyte membrane formed by a polymer ion exchange membrane and the cathode-side electrode on the other surface, and providing separators on both sides. A fuel cell stack which generates a high voltage is formed by layering a plurality of the fuel battery cells and sandwiching the plurality of fuel battery cells with a collector plate, an insulating plate, and an end plate.
In such a fuel cell, a fuel gas such as, for example, a gas including hydrogen is supplied to the anode-side electrode and an oxidation gas such as, for example, air is supplied to the cathode-side electrode. With this process, the fuel gas and the oxidation gas are supplied for reaction in the cell, an electromotive force is generated, and water is produced at the cathode-side electrode.
A gas supply channel for supplying oxygen gas to the fuel cell stack is provided and an air compressor which is a gas compressor is provided upstream of the gas supply channel. A configuration has been considered in which an intercooler is provided partway on the gas supply channel, between the air compressor and the fuel cell so that, even when the temperature of the oxidation gas such as air compressed by the air compressor is increased, the oxidation gas is cooled and introduction, into the fuel cell stack, of a high-temperature oxidation gas having an excessively increased temperature is prevented. More specifically, if the oxidation gas having the excessively increased temperature is introduced to the fuel cell stack, constituent elements of the fuel cell stack such as the electrolyte membrane in the fuel cell stack may be thermally degraded. However, when an intercooler is provided, thermal degradation may be effectively prevented. When an intercooler is provided, a coolant channel for cooling the intercooler and a coolant pump on a partway on the coolant channel are also provided. In addition, the coolant such as cooling water is circulated through the coolant channel by the coolant pump.
Even when the intercooler is provided in the fuel cell system as described above, if an abnormality such as failure occurs in the constituent elements of a cooling section for cooling the intercooler, such as the coolant pump, it may not be possible for the intercooler to prevent excessive temperature increase in the oxidation gas to be sent to the fuel cell stack. In consideration of this, in a fuel cell system described in JP 2002-184435 A, when occurrence of an abnormality in the cooling system for cooling a heat exchange device which corresponds to the intercooler is detected, a controlling device stops the air compressing device. Because of this structure, when an abnormality occurs in the cooling system of the heat exchange device, the power generation operation by the fuel cell is always stopped, irrespective of other conditions.
However, even when an abnormality occurs in the cooling system of the heat exchange device for cooling the gas to be sent to the fuel cell, no problem is presented by continuing to generate power in the fuel cell if the temperature of the oxidation gas to be sent to the fuel cell is not excessively increased.
In view of these circumstances, the present inventors have conceived that the power generation operation time of the fuel cell can be extended if power can be generated in the case where there is no problem in the power generation by the fuel cell would not present a problem even when an abnormality occurs in the cooling section of the heat exchange device.
An object of the present invention is to provide a fuel cell system in which the power generation operation time of the fuel cell can be extended by allowing power generation when there is no problem in power generation by the fuel cell even when an abnormality occurs in the cooling section of the intercooler including the coolant pump.